Diaphragm foam pump for foam dispensers and refill units

ABSTRACT

A refill unit for a foam dispenser including a liquid container and a diaphragm foam pump connected to the liquid container and diaphragm foam pumps. The diaphragm foam pump includes an elastomeric diaphragm having an air piston bore and a bellows. The air piston bore forms at least a portion of an air chamber. A reservoir is located at least partially within the bellows that includes a liquid inlet. The diaphragm foam pump includes a piston that forms a portion of the air chamber wherein the piston bore may be moved relative to the piston. Movement in a first direction causes air in an air chamber to be compressed and draws liquid into the reservoir and further movement in the same direction causes compressed air to flow into the reservoir where it mixes with the liquid and is expelled as a foam.

TECHNICAL FIELD

The present invention relates generally to foam pumps and more particularly to diaphragm foam pumps for a foam dispensing system and refill units for the same.

BACKGROUND OF THE INVENTION

Liquid dispensers, such as liquid soap and sanitizer dispensers, provide a user with a predetermined amount of liquid upon the actuation of the dispenser. It is sometimes desirable to dispense the liquids in the form of foam by, for example, injecting air into the liquid to create a foamy mixture of liquid and air bubbles. Many prior art foam pumps have many parts which add to the complexity and cost of the pump.

SUMMARY

A refill unit for a foam dispenser including a liquid container and a diaphragm foam pump connected to the liquid container is disclosed herein. The diaphragm foam pump includes an elastomeric diaphragm having an air piston bore portion and a bellows portion. The air piston bore portion forms at least a portion of an air chamber. In addition, a reservoir is located at least partially within the bellows. The reservoir includes a liquid inlet. In addition, the diaphragm foam pump includes a piston that forms at least a portion of the air chamber. The piston bore may be moved relative to the piston. Movement of the air piston bore portion in a first direction causes air in the air chamber to be compressed and draws liquid into the reservoir and further movement of the air piston bore in the same direction causes compressed air to be released from the air chamber and to flow into the reservoir where it mixes with the liquid and is expelled as a foam.

A plurality of diaphragm foam pumps are disclosed herein. In one embodiment, a diaphragm foam pump includes an elastomeric diaphragm having an air piston bore portion and a bellows portion. The air piston bore portion is located at least partially within the bellows portion. A reservoir is located within the bellows. The reservoir includes a liquid inlet and an air inlet. A piston post is also included and the piston bore moves relative to the piston post to compress air. Movement of the piston bore portion of the elastomeric diaphragm causes liquid to be drawn into the reservoir and causes air to be forced into the reservoir to mix with the liquid.

Embodiments of diaphragm foam pumps may include a housing for connecting the diaphragm foam pump to a liquid container; a piston post secured to the housing; a shell configured to at least partially fit within a neck of the liquid container and held in place by the housing. The shell may include a cylinder and a liquid inlet. In addition, a elastomeric diaphragm located at least partially between the shell and the housing. The elastomeric diaphragm includes a bellows and a piston bore. The piston bore has an opening in one end and is sized to fit over the piston post to form an air chamber and the piston bore is configured to fit at least partially within the cylinder of the shell. Movement of the piston bore over the piston post compresses the air chamber and accordingly compresses air located therein. The compressed air travels between the outside of the piston bore and the cylinder into the bellows where it mixes with the liquid and is expelled out of the pump as a foam.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features and advantages of the present invention will become better understood with regard to the following description and accompanying drawings where:

FIG. 1 illustrates an electronically activated foam soap dispenser having a diaphragm foam pump in accordance with an embodiment of the present invention;

FIG. 2 is an exploded prospective view of an exemplary diaphragm foam pump;

FIG. 3 illustrates an exploded cross-sectional view of the exemplary diaphragm foam pump of FIG. 2;

FIG. 4 illustrates a cross-sectional view of the diaphragm foam pump of FIG. 2 connected to a container with the diaphragm foam pump in a contracted position;

FIG. 5 illustrates a cross-sectional view of the diaphragm foam pump of FIG. 4 in an extended position; and

FIG. 6 illustrates another exploded cross-sectional view of an exemplary embodiment of a diaphragm foam pump; and

FIG. 7 illustrates a cross-sectional view of another embodiment of a diaphragm foam pump.

DETAILED DESCRIPTION

FIG. 1 illustrates an exemplary embodiment of an electronic dispensing unit 100 having a diaphragm foam pump 108. Electronic dispensing unit 100 includes a housing 102 and door 104 connected thereto by hinge 103. Mounted to housing 102 is an electronic power source 112, such as for example, a battery power source; an actuator 110 and a sensing unit 116. Sensing unit 116 detects the presence of an object and causes actuator 110 to dispense a dose of foam. Optionally, actuator 110 may be a manual actuator, such as for example a lever or push bar and sensing unit 116 would not be required. A refill unit 105 including a liquid container 106 and diaphragm foam pump 108. Refill unit 105 releasably connects to housing 102 by, for example, sliding into a cradle (not shown).

An exemplary embodiment of a diaphragm foam pump 108 is illustrated in FIGS. 2 and 3. FIG. 2 is an exploded prospective view of diaphragm foam pump 108 and FIG. 3 is an exploded cross-sectional view of diaphragm pump 108. This embodiment consists of three main components, a shell 210, a diaphragm 240 and a housing 260. Shell 210 includes cylinder 212. In one embodiment, cylinder 212 is open on the top and bottom. In addition, shell 210 includes a liquid inlet 214. A one-way check valve, such as a duck-bill valve 300 (FIG. 3) is connectable to liquid inlet 214 to allow liquid to enter diaphragm foam pump 108 from liquid container 106. Duck-bill valve 300 may be connected to liquid inlet 214 by, for example, a friction fit or a cap member (not shown). Shell 210 may be made of any material, and in one embodiment is made of a polyolefin resin. Other suitable materials include polyvinyl chloride (“PVC) or other plastic or resin material. Shell 210 has a base 302 that has a first projection 304 and a second projection 306 that form an annular channel 308. When the diaphragm foam pump 108 is connected to a container 106, the mouth of the container 106 (FIG. 1) fits within annular channel 308 and creates a liquid tight seal between the diaphragm foam pump 108 and container 106. In addition, shell 210 has projection member 312 (FIG. 3). Projection member 312 forms a portion of a passageway when positioned over diaphragm 240. Shell 210 also includes alignment member 310. Alignment member 310 fits within outlet cylinder 352 of diaphragm 240 to properly align shell 210 and diaphragm 240. In some embodiments, alignment member 310, if used, only needs to be long enough to extend below the top lip of the outlet cylinder 352.

Diaphragm 240 is molded from an elastomeric material, such as, for example, a thermoplastic elastomer (“TPE”), thermoplastic rubber (“TPR”), thermoplastic vulcanizate (“TPV”). Other suitable material may include rubber, EPDM, Nitrile, Silicon, etc. Diaphragm 240 includes piston bore 242, sealing plate 243, aperture 245 through sealing plate 243 leading to outlet cylinder 350, a one-way outlet check valve 246 and a compressible reservoir 244, such as a bellows. Preferably, diaphragm 240 is constructed of a unitary piece. Optionally, certain portions, such as outlet valve 246, are constructed separately and attached to diaphragm 240. In one embodiment, one-way outlet valve 246 is a duck-bill valve that is integrally formed with diaphragm 240, but may be any type of one-way outlet valve and may be secured to diaphragm 240 rather than integrally formed therewith. Sealing plate 243 has an opening located in the center that has a sloped wall 350. Sloped wall 350 forms a passageway with projection member 302 of shell 210 when the pump 108 is assembled. Sloped wall 350 leads to a bellows 244 which extends below the top surface of sealing plate 243. Bellows 244 partially surrounds piston bore 242 which extends up above sealing plate 243. Bellows 244 and piston bore 242 are joined at their respective bottom portions.

Bellows 244 is expandable and contractible and has an engagement member 250 located near the bottom of the bellows 244. In one embodiment, bellows 244 may be replaced by a dome pump, wherein the dome is expandable and contractible. Engagement member 250 allows an actuator (not shown) to move the piston bore 242 up and down and compress and expand bellows 244. Piston bore 242 has a sealing member 248 and is sized to fit within cylinder 212. Sealing member 248 is molded as an integral part of piston bore 242. Optionally, sealing member 248 may be formed as a separate part, such as for example, and o-ring secured to piston bore 242 by for example, a recess (not shown). Sealing member 242 forms an airtight and liquid tight seal between piston bore 242 and the inside wall of cylinder 212 when diaphragm foam pump 108 is assembled. In addition, piston bore 244 has a horizontal slit-valve 344 formed in its side wall. Horizontal slit-valve 344 may be formed by, for example, stretching the elastomeric material, slitting the material and letting the material contract. Such a process creates a slit in the material with edges that mate under normal conditions and pressure is required to allow air to pass there-thorough. Horizontal slit-valve 344 opens only under pressure to allow air to flow out of air chamber 354 in piston bore 242 to an area in the piston bore 242 and cylinder 212. In one embodiment, horizontal slit valve 344 comprises one or more small apertures, such as small pin holes. Along the bottom interior of piston bore 242 are longitudinal recesses 348 and corresponding ribs 349. Piston bore 242 is sized to snugly fit over piston post 266.

Piston post 266 is a portion of hosing 260 and piston bore 242 rides up and down on piston post 266. Housing 260 also includes a cap 360 having threads 362 for securing diaphragm foam pump 108 to container 106. Housing 260 has a base 363 with a first aperture 364 leading into cylinder 366. Outlet cylinder 352 and one-way outlet valve 246 of diaphragm 240 fit within and extending through cylinder 366. Base 363 includes a second aperture 368. Bellows 244 and air piston bore 242 of diaphragm 240 fit through aperture 368 when the pump is assembled. Housing 260 also includes one or more support arms 262 and 264 that are connected to base 268. Base 268 supports piston post 266. Support arms 262 and 264 should be rigid enough to ensure piston post 266 has little to no movement with respect to housing 260 during operation.

FIG. 4 is a cross-sectional view of refill unit 400 that includes diaphragm foam pump 108 connected to container 106. Diaphragm foam pump 108 is shown with bellows 244 in its compressed position and piston bore 242 at the top of its stroke. With piston bore 242 at the top of its stroke longitudinal grooves 348 provide a pathway for air to enter air chamber 410. Bellows 244 is compressed/expanded and piston bore 242 is moved up/down by an actuator (not shown) that engages with actuating member 250. As actuating member 250 is moved down toward its lowest position (FIG. 5), a vacuum is created in reservoir 404 in bellows 244 causing one-way outlet valve 246 to seal and one-way inlet valve 300 to open allowing liquid to flow through inlet chamber 401 through passage 402 (which is created between sloped wall 350 and projecting member 312, which are shown in FIG. 3) and into reservoir 404. Simultaneously, air is being compressed in air chamber 410. Upon buildup of sufficient air pressure, horizontal slit valve 344 opens and compressed air passes into passageway 412 located between the outside wall of piston bore 242 and the inside wall of cylinder 212. The compressed air flows into reservoir 404 and mixes with and aerates the liquid to form a foamy mixture of liquid and air. Air is prevented from flowing up into liquid container 106 by cylinder 212 and sealing member 342. The foamy mixture is forced out of reservoir 404 through passage 406 into outlet reservoir 408. In one embodiment, passage 406 is sized small enough that the foamy mixture passes through at an increased velocity causing further aeration and an increase in the quality of the foam as it passes into outlet reservoir 408 and through one-way outlet valve 246 where it is dispensed as a foam.

As actuating member 240 is moved to its upper position shown in FIG. 5, the bellows 244 compresses and expels any residual mixture of liquid and air from reservoir 404. In addition, a vacuum is created in air chamber 410. Once a portion of longitudinal grooves 348 moves above piston post 266, air is drawn into air chamber 410. Actuating member 250 is pulled back down to dispense another dose.

FIG. 6 illustrates an exploded cross-sectional view of another exemplary embodiment of a diaphragm foam pump 600. This embodiment is similar to the embodiment disclosed in FIG. 3 and like-numbered components are not re-described with respect to this embodiment. Shell 610 includes an integrally formed liquid inlet tube 614. The top of liquid inlet tube 614 extends slightly above the base 302. Inlet tube 614 provides a liquid passageway from a liquid container into the diaphragm foam pump 600. A cap 602 is secured to the top of liquid passageway 614. Cap 602 may be secured with a friction fit, threads, an adhesive, welding, thermal bonding or any other means to secure cap 602 to liquid inlet tube 614. Cap 602 includes an aperture therethrough that contains a one-way check valve 604 to allow liquid to enter the diaphragm foam pump through liquid inlet tube 614, but prevents liquid from flowing out of the diaphragm foam pump through liquid inlet tube 614. One-way check valve 604 may be any one-way check valve, such as for example, an umbrella valve, a duck-bill valve, a plug valve, a flapper valve, or the like. Preferably one-way check valve 604 requires vacuum pressure to open so that a vacuum must be created in the liquid reservoir before liquid flows into the liquid reservoir past one-way check valve 604. The remainder of shell 610 is substantially the same as shell 210.

Diaphragm 640 is substantially the same as diaphragm 240; however, outlet cylinder 640 has a different configuration than outlet cylinder 352. Outlet cylinder 640 includes a base 646 with an aperture therethrough. Outlet valve 642, which may be for example a slit valve, rests on base 646. Outlet valve 642 may be sized to fit snugly within outlet cylinder 640. In one embodiment, a retaining ring (not shown) may be pressed into outlet cylinder 604 over the top of outlet valve 642 to hold it in place. Such a retaining ring may be slightly larger in diameter than the interior diameter of elastomeric outlet cylinder 604 and thus will be held in place by the elasticity of the walls of outlet cylinder 604. Slit valve 642 has a dome shape with a slit 644 in the center. Under pressure the dome shape inverts and the foamy mixture passes through slit 644. Upon cessation of pressure, the dome reverts back to its original shape. In one embodiment, slit valve 642 sucks back residual foamy mixture as it reverts back to its original shape.

In this embodiment, housing 660 has a modified cylinder 662. Cylinder 662 has an outlet nozzle 666 formed by tapered walls 664 of cylinder 662. In one embodiment, a foam generator 668 is placed in cylinder 662 prior to assembly of the diaphragm foam pump 600. Accordingly, the foamy mixture may be further enhanced by being forced through the foam generator 668 as it is expelled from the diaphragm foam pump.

FIG. 7 illustrates a cross-sectional view of yet another refill unit 700 having a diaphragm foam pump 701 in accordance with an embodiment of the present invention. Diaphragm foam pump 700 is similar to the diaphragm foam pump 108 shown and described in FIGS. 2-5 and like-numbered elements are not described in detail with respect to FIG. 7. In this embodiment, piston bore 742 is similar to piston bore 242 except that piston bore 742 does not include longitudinal recesses 348 and corresponding ribs 349. In this exemplary embodiment, piston post 766 includes a top plate 704 that has an aperture therethrough. A one-way check valve 706 is located in the aperture. One-way check valve allows air to enter the air chamber 710 during the upstroke of piston bore 742. Advantages to using such an embodiment, may be, for example, the ability to alter the stroke length of piston bore 742 because there is no requirement to move the end of piston bore 742 to a certain position prior to air entering into the air chamber 710. In addition, because less of a vacuum is created in air chamber 710 than is created in air chamber 410 during the upstroke, it takes less energy to operate pump 701 than it does to operate pump 108.

While the present invention has been illustrated by the description of embodiments thereof, and while the embodiments have been described in considerable detail, it is not the intention of the applicants to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. For example, molding both the inlet and outlet valve into the elastomeric diaphragm makes it possible to fabricate the entire pump with three parts. Therefore, the invention, in its broader aspects, is not limited to the specific details, the representative apparatus and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of the applicants' general inventive concept. 

I/We claim:
 1. A refill unit for a foam dispenser comprising: a liquid container and a diaphragm foam pump connected to the liquid container; the diaphragm foam pump including; an elastomeric diaphragm having an air piston bore portion and a compressible reservoir portion formed as a unitary piece; the air piston bore portion forming at least a portion of an air chamber; a liquid inlet into the compressible reservoir; a piston forming at least a portion of the air chamber, wherein the piston bore moves relative to the piston to compress air; wherein movement of the air piston bore portion relative to the piston in a first direction causes air in the air chamber to be compressed and draws liquid into the reservoir and wherein further movement of the air piston bore causes compressed air to be released from the air chamber and to flow into the reservoir.
 2. The refill unit of claim 1 wherein the piston is stationary and the compressible reservoir is a bellows.
 3. The refill unit of claim 2 wherein the air piston bore has a slit valve located in a wall.
 4. The refill unit of claim 2 wherein the air piston bore is located at least partially within the reservoir.
 5. The refill unit of claim 2 wherein the piston is secured to a cap which connects to the liquid container.
 6. The refill unit of claim 2 further comprising an outlet passage from the reservoir that has a first cross-sectional area that is different than a second cross-sectional area.
 7. The refill unit of claim 2 further comprising one or more recesses in the piston bore for allowing air to enter the air chamber.
 8. A diaphragm foam pump comprising: an elastomeric diaphragm having an air piston bore portion and a bellows portion, wherein the air piston bore portion is located at least partially within the bellows portion; a reservoir at least partially formed by the bellows and the outside of the piston bore portion; a liquid inlet into the reservoir; a piston post, wherein the piston bore moves relative to the piston post to compress air; an air inlet into the reservoir; wherein movement of a portion of the elastomeric diaphragm causes liquid to be drawn into the reservoir and causes air to be forced into the reservoir to mix with the liquid.
 9. The diaphragm foam pump of claim 8 comprising an air outlet in a wall of the air piston bore wherein the air is sized to restrict air flow therethrough.
 10. The diaphragm foam pump of claim 9 wherein the air outlet is a slit valve.
 11. The diaphragm foam pump of claim 8 further comprising an outlet passage that has a first portion with a first cross-sectional area and a second portion with a second cross-sectional area that is greater than the first.
 12. The diaphragm foam pump of claim 8 wherein the piston post is secured to a cap that is securable to a liquid container.
 13. The diaphragm foam pump of claim 8 further comprising a container filled with a foamable liquid.
 14. The diaphragm foam pump of claim 8 wherein the liquid inlet passage is formed between a portion of a shell and the diaphragm.
 15. A diaphragm foam pump comprising: a housing for connecting the diaphragm foam pump to a liquid container; a piston post secured to the housing; a shell configured to at least partially fit within a neck of the liquid container and held in place by the housing; the shell having a cylinder and a liquid inlet located therein; an elastomeric diaphragm located at least partially between the shell and the housing; the elastomeric diaphragm having a bellows and a piston bore; the piston bore having an opening in one end sized to fit over the piston post to form an air chamber; the piston bore configured to fit at least partially within the cylinder of the shell; wherein movement of the piston bore over the piston post compresses the air chamber and compresses air located therein; and compressed air travels between the outside of the piston bore and the cylinder into the bellows.
 16. The diaphragm foam pump of claim 15 further comprising an outlet duck-bill valve.
 17. The diaphragm foam pump of claim 15 wherein the piston bore has a slit valve through one of its walls for the compressed air to pass therethrough.
 18. The diaphragm foam pump of claim 15 wherein the outlet valve is integrally formed with the elastomeric diaphragm.
 19. The diaphragm foam pump of claim 15 wherein the piston bore comprises one or more elongated recesses for allowing air to enter the air chamber.
 20. The diaphragm foam pump of claim 15 wherein the elastomeric diaphragm further comprises an actuator member for engaging with a dispenser actuator. 